A Chemical Diffusion‐Controlled Electrode Reaction at the Compact La1 − x Sr x MnO3/Stabilized Zirconia Interface in Oxygen Atmospheres

Abstract

In order to elucidate how the oxide‐ion electron mixed conduction in an oxide cathode affects the kinetics of the cathode reaction in solid oxide fuel cells, a compact layer was prepared as a working electrode on the electrolyte of 3 mole percent doped by a laser flash evaporation method, and electrochemical measurements were made as a function of oxygen partial pressures, , at 700 to 900°C. Contrary to the case of a porous electrode system, the electrode interface conductivity was found to increase with decreasing . With large anodic polarization, the oxide layer was found to be peeled off by oxygen evolution at the electrode/stabilized zirconia interface. The kinetics controlled by chemical diffusion of oxygen in the oxide layer were observed under cathodic polarization with Pa at 900°C. The oxide ion conductivity in was found to be proportional to , where aO is the oxygen activity in the oxide.